Electrically conductive polymers from the class of polypyrroles, polyanilines and polythiophenes are known from the literature. Poly(3,4-alkylenedioxythiophene) dispersions in particular have recently acquired technical importance, since they can be used, for example, for the production of conductive or antistatic coatings (see e.g. EP-A 440 957). In practice, however, it has been found that the electrical conductivity of the coatings from such dispersions is not always sufficiently stable for practical uses under a higher temperature and/or UV irradiation.
EP 1798259 A1 and WO 2008/055834 A1 disclose that e.g. the heat stability or UV stability of the electrical conductivity of coatings comprising polythiophene dispersions can be increased if derivatives of gallic acid (3,4,5-trihydroxybenzoic acid), such as, for example, gallic acid propyl ester, are added. Nevertheless, this stabilizing action, in particular the action on the heat stability, is not sufficient for many long-term uses.
There thus continued to be a need for conductive or antistatic coatings with improved heat or UV stability compared with the known coatings and for suitable dispersions for the production of such coatings.